Re: [PATCH v3 01/12] PCI: rockchip-ep: Fix address translation unit programming

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Thu, Oct 10, 2024 at 05:41:56PM +0900, Damien Le Moal wrote:
> On 2024/10/10 16:02, Manivannan Sadhasivam wrote:
> > On Mon, Oct 07, 2024 at 01:12:07PM +0900, Damien Le Moal wrote:
> >> The rockchip PCIe endpoint controller handles PCIe transfers addresses
> >> by masking the lower bits of the programmed PCI address and using the
> >> same number of lower bits masked from the CPU address space used for the
> >> mapping. For a PCI mapping of <size> bytes starting from <pci_addr>,
> >> the number of bits masked is the number of address bits changing in the
> >> address range [pci_addr..pci_addr + size - 1].
> >>
> >> However, rockchip_pcie_prog_ep_ob_atu() calculates num_pass_bits only
> >> using the size of the mapping, resulting in an incorrect number of mask
> >> bits depending on the value of the PCI address to map.
> >>
> >> Fix this by introducing the helper function
> >> rockchip_pcie_ep_ob_atu_num_bits() to correctly calculate the number of
> >> mask bits to use to program the address translation unit. The number of
> >> mask bits iscalculated depending on both the PCI address and size of the
> >> mapping, and clamped between 8 and 20 using the macros
> >> ROCKCHIP_PCIE_AT_MIN_NUM_BITS and ROCKCHIP_PCIE_AT_MAX_NUM_BITS.
> >>
> > 
> > How did you end up with these clamping values? Are the values (at least MAX
> > applicable to all SoCs)?
> > 
> > Btw, it would be helpful if you referenced the TRM and the section that
> > describes the outbound mapping. I'm able to find the reference:
> > 
> > Rockchip RK3399 TRM V1.3 Part2, Section 17.5.5.1.1
> 
> OK. Will add that.
> 
> I really appreciate very much all the reviews you are sending, but given that
> this patch series depends on the series "[PATCH v4 0/7] Improve PCI memory
> mapping API", could we start with that one and get it queued ASAP ?
> 

Sure. Sorry for being late btw. Personal errands are eating up the review time.

- Mani

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